To reduce the burning loss and the spalling and to improve energy efficiency,the mullite composite lining plates were used to replace cast steel or alloy lining in rotary coke tanks for coke dry quenching equipment.Th...To reduce the burning loss and the spalling and to improve energy efficiency,the mullite composite lining plates were used to replace cast steel or alloy lining in rotary coke tanks for coke dry quenching equipment.The results show that:the dense mullite composite lining plate in the cone part has the density of 2.20 g·cm^(-3) and the wear test,s volume loss of 4.08 cm^(3),and the light weight mullite composite lining plate in the straight cylinder part has the density of 1.95 g·cm^(-3) and the wear test,s volume loss of 17.6 cm^(3).After using,there is no shrinkage gap,no burn loss or holes in the plates,indicating good sealing of the mullite composite lining plates.The lining plate for the cone part has low burning loss,without spalling for more than half a year.The outer surface temperature of coke tanks adopting the cast steel or the alloy lining is 480 to 570℃,while that of the ones adopting mullite composite lining plates is 120 to 170℃,showing a largely improved insulating property.Adopting mullite composite lining plates on the basis of the current coke tank cage,the lining plates can be timely treated and wholly replaced,improving the service life and reducing the maintenance workload.展开更多
The mullite-SiC castables for coke dry quenching（CDQ）furnace corbel pillar were prepared by taking mullite and silicon carbide as aggregates,silicon carbide powder,fused silica powder,α-Al2O3powder and silica fume ...The mullite-SiC castables for coke dry quenching（CDQ）furnace corbel pillar were prepared by taking mullite and silicon carbide as aggregates,silicon carbide powder,fused silica powder,α-Al2O3powder and silica fume as matrix,calcium aluminate cement as binding system,and extra-adding steel fibers to extend the CDQ furnace refractory life.The effects of steel fiber types（melt pumping meniscus,cut straight,wavy indentation,cold-drawn hook）and steel fiber extra-additions（0,1%,2%,3%by volume）on the properties of mullite-SiC castables were investigated.Then the toughening mechanism of steel fiber in the castables was analyzed according to the load-displacement curves.The results show that：（1）the toughening effects of the melt pumping meniscus steel fiber with rough surface and colddrawn hook steel fiber with strong anchoring effect with the matrix are better than those of cut straight steel fiber and wavy indentation steel fiber;（2）the suitable amount of steel fiber（less than 2%）in mullite-SiC castables not only significantly improves the mechanical properties,thermal shock resistance and wearing resistance,but also improves the fracture energy by 49.0%and slows the crack growth;（3）the bond strength and mechanical anchoring force between steel fiber and castable interface are key elements of steel fiber reinforced castables.展开更多
In order to prolong the service life of the cooling zone of large scale coke dry quenching ovens,six kinds possible refractories for the cooling zone of large scale coke dry quenching ovens： SiC containing brick A,Si...In order to prolong the service life of the cooling zone of large scale coke dry quenching ovens,six kinds possible refractories for the cooling zone of large scale coke dry quenching ovens： SiC containing brick A,SiC containing brick B,mullite-andalusite brick,spinel containing brick,zirconia containing brick,corundum-mullite brick and grade B mullite brick,were analyzed in properties. It is found that the cooling zone lining adopting SiC containing bricks or mullite-andalusite bricks has much longer service life. Based on this,a new type of wear resistant brick was developed. The brick has a compressive strength of 135 MPa,a wear loss of 2. 10cm^3（only a quarter of that of the grade B mullite brick）,and a higher bulk density than the grade B mullite brick. The application of the brick in a 140t·h^（-1）coke dry quenching oven showed that it performed better than the grade B mullite brick. The cooling zone adopting the new bricks has a lower coke discharging temperature,which is beneficial to the enhancement of heat recovery efficiency and steam power generation.展开更多
The mechanism of coke size segregation in the radial direction of pre-chamber in coke dry quenching （CDQ） shaft was investigated by experiment and numerical analysis. The experimental apparatus was a cold three-dime...The mechanism of coke size segregation in the radial direction of pre-chamber in coke dry quenching （CDQ） shaft was investigated by experiment and numerical analysis. The experimental apparatus was a cold three-dimensional semicircle model for bell-type charging, which was used to study the influences of different kinds of bells and different stock line levels on the radial distribution of coke size in the radial direction of a pre-chamber. A mathematical model was used, which is capable of estimating the radial average size distribution as well as the radial deposit distribution of each particle size for multiple size coke with a few fixed parameters. The calculated results agree well with the experimental data, which proves the reliability of both experimental study and numerical analysis.展开更多
The mechanical force borne by the lintel and“brackets”in the inclined channel area of CDQ and the thermal stress generated by the top-down temperature gradient were simulated by ANSYS software.The following conclusi...The mechanical force borne by the lintel and“brackets”in the inclined channel area of CDQ and the thermal stress generated by the top-down temperature gradient were simulated by ANSYS software.The following conclusions are drawn.(1)The mechanical force has very mild effect on the damage of the“brackets”.(2)The temperature gradient caused by the uneven temperature distribution of CDQ oven is the key factor affecting the“bracket”damage.The different expansion of refractory materials in various parts results in the thermal stress concentration which tears the“brackets”.(3)The structure adjustment of the“brackets”has very little effect on the thermal stress distribution.(4)The multi-phase nitride bonded silicon carbide for CDQ can effectively alleviate the stress concentration at the“brackets”,realizing the long-life and stable operation.展开更多
A mathematical model based on non-Darcian flow and two-phase model is developed for fluid flow and heat transfer in the cooling shaft of Coke Dry Quenching (CDQ) unit. The potential flow model is employed to simulate ...A mathematical model based on non-Darcian flow and two-phase model is developed for fluid flow and heat transfer in the cooling shaft of Coke Dry Quenching (CDQ) unit. The potential flow model is employed to simulate coke descending. Governing equations are solved by the SIMPLE algorithm on the collocated, non-orthogonal and body-fitted grids. The velocity of circulating gas and the temperature of coke and gas are obtained to study the effects of coke size distribution on flow and heat transfer behavior in the cooling shaft. It is found that the non-uniformity of gas velocity and the unevenness of coke temperature in the radial direction can be reduced if coke size distribution is improved. The gas velocity field and the temperature distribution of coke and gas are presented.展开更多
Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical mo...Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical model developed for the cooling process of real CDQ shaft, the one-seventh scale experimental setup was established. With the air as the working fluid and the coke as the packed bed, the coke and gas temperatures and the pressure drop in the cooling shaft were measured. A mathematical model based on the non-Darcian and non-thermal equilibrium model for the cooling process of the CDQ experimental shaft was presented. The computational results were compared to the experimental data. It was found that most numerical predictions were supported by the measured values.展开更多
During the operation of a coke dry quenching system of coking plant, wear-proofing cover of the boiler was seriously eroded, and even the ceiling tube of the boiler was worn and torn. Thus, attentions were paid to the...During the operation of a coke dry quenching system of coking plant, wear-proofing cover of the boiler was seriously eroded, and even the ceiling tube of the boiler was worn and torn. Thus, attentions were paid to the research, development and application of the wear-resistant coating spraying technique for wear-proofing cover of the coke dry quenching furnace. The Cr3C2–NiCr coatings for wear-proofing cover were fabricated via supersonic arc spraying process, and the residual coating of wear-proofing cover would be sampled for being analyzed after two years. The coating presents a dense microstructure with few pores and micro-cracks (the porosity is 4.65%). After thermal spraying of the wear-proofing cover, the hardness and the wear resistance of the surface are improved. The remaining coating is continuous and compact, with an average thickness of about 147μm. Transverse micro-cracks parallel to the spreading direction of the coating surface are displayed on different areas of the coating, which demonstrates its serious erosion wear effect. The main chemical component of white zone is Fe–18Cr–Ni. The Cr level of light gray phase is about 77.57 wt.% and the O level is 22.43 wt.%. And the main chemical components of dark gray phase are C, O, Al, Si and Ca. X-ray diffraction patterns were adopted to implement phase analysis on the surface of coating sample, which indicated that the coating was composed of a large amount of Cr3O2 and a small amount of metal Cr.展开更多
文摘To reduce the burning loss and the spalling and to improve energy efficiency,the mullite composite lining plates were used to replace cast steel or alloy lining in rotary coke tanks for coke dry quenching equipment.The results show that:the dense mullite composite lining plate in the cone part has the density of 2.20 g·cm^(-3) and the wear test,s volume loss of 4.08 cm^(3),and the light weight mullite composite lining plate in the straight cylinder part has the density of 1.95 g·cm^(-3) and the wear test,s volume loss of 17.6 cm^(3).After using,there is no shrinkage gap,no burn loss or holes in the plates,indicating good sealing of the mullite composite lining plates.The lining plate for the cone part has low burning loss,without spalling for more than half a year.The outer surface temperature of coke tanks adopting the cast steel or the alloy lining is 480 to 570℃,while that of the ones adopting mullite composite lining plates is 120 to 170℃,showing a largely improved insulating property.Adopting mullite composite lining plates on the basis of the current coke tank cage,the lining plates can be timely treated and wholly replaced,improving the service life and reducing the maintenance workload.
文摘The mullite-SiC castables for coke dry quenching（CDQ）furnace corbel pillar were prepared by taking mullite and silicon carbide as aggregates,silicon carbide powder,fused silica powder,α-Al2O3powder and silica fume as matrix,calcium aluminate cement as binding system,and extra-adding steel fibers to extend the CDQ furnace refractory life.The effects of steel fiber types（melt pumping meniscus,cut straight,wavy indentation,cold-drawn hook）and steel fiber extra-additions（0,1%,2%,3%by volume）on the properties of mullite-SiC castables were investigated.Then the toughening mechanism of steel fiber in the castables was analyzed according to the load-displacement curves.The results show that：（1）the toughening effects of the melt pumping meniscus steel fiber with rough surface and colddrawn hook steel fiber with strong anchoring effect with the matrix are better than those of cut straight steel fiber and wavy indentation steel fiber;（2）the suitable amount of steel fiber（less than 2%）in mullite-SiC castables not only significantly improves the mechanical properties,thermal shock resistance and wearing resistance,but also improves the fracture energy by 49.0%and slows the crack growth;（3）the bond strength and mechanical anchoring force between steel fiber and castable interface are key elements of steel fiber reinforced castables.
文摘In order to prolong the service life of the cooling zone of large scale coke dry quenching ovens,six kinds possible refractories for the cooling zone of large scale coke dry quenching ovens： SiC containing brick A,SiC containing brick B,mullite-andalusite brick,spinel containing brick,zirconia containing brick,corundum-mullite brick and grade B mullite brick,were analyzed in properties. It is found that the cooling zone lining adopting SiC containing bricks or mullite-andalusite bricks has much longer service life. Based on this,a new type of wear resistant brick was developed. The brick has a compressive strength of 135 MPa,a wear loss of 2. 10cm^3（only a quarter of that of the grade B mullite brick）,and a higher bulk density than the grade B mullite brick. The application of the brick in a 140t·h^（-1）coke dry quenching oven showed that it performed better than the grade B mullite brick. The cooling zone adopting the new bricks has a lower coke discharging temperature,which is beneficial to the enhancement of heat recovery efficiency and steam power generation.
文摘The mechanism of coke size segregation in the radial direction of pre-chamber in coke dry quenching （CDQ） shaft was investigated by experiment and numerical analysis. The experimental apparatus was a cold three-dimensional semicircle model for bell-type charging, which was used to study the influences of different kinds of bells and different stock line levels on the radial distribution of coke size in the radial direction of a pre-chamber. A mathematical model was used, which is capable of estimating the radial average size distribution as well as the radial deposit distribution of each particle size for multiple size coke with a few fixed parameters. The calculated results agree well with the experimental data, which proves the reliability of both experimental study and numerical analysis.
文摘The mechanical force borne by the lintel and“brackets”in the inclined channel area of CDQ and the thermal stress generated by the top-down temperature gradient were simulated by ANSYS software.The following conclusions are drawn.(1)The mechanical force has very mild effect on the damage of the“brackets”.(2)The temperature gradient caused by the uneven temperature distribution of CDQ oven is the key factor affecting the“bracket”damage.The different expansion of refractory materials in various parts results in the thermal stress concentration which tears the“brackets”.(3)The structure adjustment of the“brackets”has very little effect on the thermal stress distribution.(4)The multi-phase nitride bonded silicon carbide for CDQ can effectively alleviate the stress concentration at the“brackets”,realizing the long-life and stable operation.
文摘A mathematical model based on non-Darcian flow and two-phase model is developed for fluid flow and heat transfer in the cooling shaft of Coke Dry Quenching (CDQ) unit. The potential flow model is employed to simulate coke descending. Governing equations are solved by the SIMPLE algorithm on the collocated, non-orthogonal and body-fitted grids. The velocity of circulating gas and the temperature of coke and gas are obtained to study the effects of coke size distribution on flow and heat transfer behavior in the cooling shaft. It is found that the non-uniformity of gas velocity and the unevenness of coke temperature in the radial direction can be reduced if coke size distribution is improved. The gas velocity field and the temperature distribution of coke and gas are presented.
基金This work has been supported by Cross-Century Talents Projects of Educational Ministry of China.
文摘Owing to its merits in energy savings, environmental protection and coke quality improvement, the Coke Dry Quenching (CDQ) technology is favorite in coke making industry today. In order to validate the mathematical model developed for the cooling process of real CDQ shaft, the one-seventh scale experimental setup was established. With the air as the working fluid and the coke as the packed bed, the coke and gas temperatures and the pressure drop in the cooling shaft were measured. A mathematical model based on the non-Darcian and non-thermal equilibrium model for the cooling process of the CDQ experimental shaft was presented. The computational results were compared to the experimental data. It was found that most numerical predictions were supported by the measured values.
基金the National Natural Science Foundation of China(Grant Nos.U1560101 and U1738I01)the National Key Research and Development Program of China(2016YFC0209302).
文摘During the operation of a coke dry quenching system of coking plant, wear-proofing cover of the boiler was seriously eroded, and even the ceiling tube of the boiler was worn and torn. Thus, attentions were paid to the research, development and application of the wear-resistant coating spraying technique for wear-proofing cover of the coke dry quenching furnace. The Cr3C2–NiCr coatings for wear-proofing cover were fabricated via supersonic arc spraying process, and the residual coating of wear-proofing cover would be sampled for being analyzed after two years. The coating presents a dense microstructure with few pores and micro-cracks (the porosity is 4.65%). After thermal spraying of the wear-proofing cover, the hardness and the wear resistance of the surface are improved. The remaining coating is continuous and compact, with an average thickness of about 147μm. Transverse micro-cracks parallel to the spreading direction of the coating surface are displayed on different areas of the coating, which demonstrates its serious erosion wear effect. The main chemical component of white zone is Fe–18Cr–Ni. The Cr level of light gray phase is about 77.57 wt.% and the O level is 22.43 wt.%. And the main chemical components of dark gray phase are C, O, Al, Si and Ca. X-ray diffraction patterns were adopted to implement phase analysis on the surface of coating sample, which indicated that the coating was composed of a large amount of Cr3O2 and a small amount of metal Cr.
